Fluid flow machine having parallel rotors



Sept. 29, 1964 N. LAING 3,150,821

FLUID FLOW MACHINE HAVING PARALLEL ROTORS Filed Sept. 5, 1962 2Sheets-Sheet l m I L 7 \I\ 7 4.9

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ATTORNEYS Sept. 29, 1964 N. LAING FLUID FLOW MACHINE HAVING PARALLELROTORS Filed Sept. 5, 1962 2 Sheets-Sheet 2 United States Patent3,150,821 FLUID FLGW MAfIHlNE HAVING PARALLEL ROTURS Nikolaus Laing,Roseuhergstrasse 24A, Stuttgart, Germany Filed Sept. 5, N62, Ser. No.221,617 Claims. (Cl. 230-117) This invention relates to a fiuid flowmachine having parallel rotors and more particularly to a fluid flowmachine of the cross-flow type having cylindrically bladed rotors andguide means associated with each of the rotors to guide air through thepath of the rotating blades into the rotors and through the path of therotating blades out of the rotors. This application is acontinuation-in-part of copending application Serial No. 671,114, filedJuly 5, 1957, now abandoned.

The invention concerns more especially a flow machine of the typedescribed comp-rising a plurality of rotors arranged side by side withtheir axes parallel and associated with guide means whereby all of theair passing through each of the rotors is discharged in the same generaldirection.

Fluid flow machines in the form of axial flow fans often used asventilating fans are not capable of utilizing the completecross-sectional area of the fan because the center of the fan is usuallytaken up by a motor which is used to rotate the fan blades. Such fansare often mounted in rectangular housings in order that the housingmight be inserted in a wall opening or in a window frame. Axial flowfans when so mounted are not able to provide air flow through thecomplete opening since the fan itself is circular and the area of thecorners of the housing beyond the periphery of the fan are closed inorder that the housing might fit in the window opening.

Centrifugal-type fans are likewise inappropriate for use as a wall fansince ducting must be provided for the inflow of air into the rotor thuspreventing complete utilization of the wall opening.

It is, therefore, an object of this invention to provide for across-flow type fluid flow machine of the type described which may, forexample, be inserted in a wall opening or window to make effective useof the complete cross-sectional area of the opening or Window.

Broadly, the invention contemplates having a plurality of bladedcylindrical rotors having guide means associated therewith such that inoperation of the machine air is caused to flow into the rotor throughthe path of the rotating blades and out of the rotor through the path ofthe rotating blades. Preferably the guide means are such to form acylindrical fluid vortex approximating a Rankine vortex with the vortexhaving its region of low static pressure parallel to the rotor axis andhaving its core interpenetrating the blade ring in order to guide flowof air through the rotor. The rotors are arranged with their axesparallel with each other. The guide means may include guide membersmovable between operative and inoperative positions wherein the guidemembers are effective to close the aperture or window frame.

Preferred embodiments of my invention are illustrated diagrammaticallyin the accompanying drawings in which,

FIG. 1 is a front view of a flow unit adapted to be inserted in a windowor wall opening;

FIG. 2 is an enlarged cross-sectional view of the unit of FIG. 1 takenalong lines II-II;

FIG. 3 is an enlarged cross-sectional view of a different embodiment ofthe flow unit a shown in FIG. 2; and

FIG. 4 is a cross-sectional view of an electric motor suitable fordriving a flow unit according to the invention.

Referring to the drawings in which the flow machine is 3,150,821Patented Sept. 29, 1964 shown as a fan, the fan unit of FIGS. 1 and 2comprises a rectangular frame 1 suitable for placement in an aperture ina wall or window. The fan comprises four similar rotors 2, 3, 4, and 5,mounted horizontally one above another with their axes parallel and allcontained in the same vertical plane. Each rotor is divided into twoequal sections such as the sections of rotor 2 designated 2a and 2b. Acentral vertical pillar 6 extends between upper and lower horizontalmembers of the frame 1 and carries the driving means 7 for the rotors2-5 which means are not shown in detail. Each driving means supports apair of rotor sections and is situated intermediate those sections. Aform of motor suitable for driving the rotors is shown in FIG. 4.

Each rotor section, for example section 2a, comprises rotor blades 8mounted parallel to the rotor axis with inner and outer edges of theblades lying on cylindrical envelopes, the blades being concave facinthe direction of rotation and having their outer edges leading theirinner edges. The driving means or a part rotating therewithsubstantially closes one end of the rotor section 2a. The other end ofthe rotor section 2a, where the blades are preferably interconnected andrigidified by a ring not shown, lies adjacent a vertical member of theframe 1 and is separated therefrom by only a working clearance (whichfor clarity is shown magnified in the figure). Thus, this end of therotor section is also substantially closed. Rotation of the rotor takesplace in the direction indicated 'by the arrow iii.

A series of guide members designated generally 14 extend horizontallywith constant cross-section between the vertical members of the frame 1,interrupted only by the pillar 6. The rotors 2-5 are each locatedbetween a pair of guide members 14, one above the rotor and one below,which members present upper and lower guide walls 15 and 16 thereto. Theguide walls 15 and 16 are similar for each rotor and therefore only onepair will be described.

The upper and lower guide walls 15 and 1d cooperating with the rotorsection 2a provide portions 15a and 15a converging towards the rotor onone side thereof and defining therewith an entry region 17. On the otherside of the rotor, the walls 15 and 16 diverge therefrom and define anexit region 18. The diverging portion of the upper wall 15, which isdesignated 15b, has a radius of curvature increasing monotonically fromthe line of nearest approach to the rotor. The lower wall 1a which has afirst guide surface 16a extending from one side of the frame towards therotor and a second guide surface which extends from the rotor to theopposite side of the frame and has in addition a slightly concaveportion 1612 which converges with the rotor in the direction of rotorrotation to the line of nearest approach. The wall 16, thereafter,extends towards the exit region and breaks sharply into a more stronglydivergent portion 160. The wall 16 cooperating with each of the rotors2, 3 and 4- meets the wall 15 cooperating respectively with the rotors3, 4 and 5 at an acute angle both at the entry and at the exit side ofthe unit. Thus, the fan unit draws air from virtually the whole area ofthe frame 1, and also discharges over the whole area.

The guide walls and the angles and curvature of the rotor blades 3 areso arranged that in operation the rotor 2 and the guide wall 16 form andstabilize an approximately cylindrical vortex, including a field regionwith a velocity profile approximating that of a Rankine vortex and acore region eccentric to the rotor axis (which core region is indicatedat V). The vortex formed induces a major part of the throughput to passthrough the blades where they have a component of velocity in adirection opposite to the main direction of the flow within the rotor(shown by the arrow A). That part of the wall 16 which chieflyinfluences flow through the rotor (the part 16b) extends over only asmall arc thereof so that the stream tubes of the throughput nearest thevortex core (which tubes are indicated at MF) are turned through anangle 'at least 90 in passing through the rotor and the velocity profileat the second entrance to the rotor blades has the character of thevelocity profile of a Rankine vortex. The major part of the throughputis associated with the flow tubes MP.

A ventilating fan for use in the wall or window of a room is limited asto peripheral speed since too great a speed will give rise toobjectionable noise. Motor speed will normally be a design datum and inconjunction with the limitations on peripheral speed will drasticallyrestrict the rotor diameter. Flow therefore necessarily takes placeunder conditions of low Reynolds numbers where conventional type fansare inefficient. The features just described lead to a great improvementin efliciency under such conditions, over what has hitherto beenregarded as acceptable. The arrangement of the rotors side by side withtheir axes parallel enables any desired throughput to be handled despitethe restrictions on rotor diameter. Thus a fan unit according to thepresent invention can be both more compact and more silent than a unitof equivalent throughput belonging to the types hitherto in common use,such as an axial flow fan unit.

The fan unit just described has the further advantage over axial fanshitherto commonly used for ventilation in that it is little effected byback pressure, such as might be produced by a wind blowing against theoutlet side of the unit, or alternatively, by the suction necessary tobring fresh air into a closed room where the air must pass under doorsand through like restricted passages.

The fan unit of FIG. 3 includes two similar rotors 3t and 31 mounted oneabove the other with, their axes horizontal within a frame designatedgenerally 32. Shafts 30a and 31a driven by means not shown support therotor, but apart from these shafts, the interiors of the rotors areclear of obstruction. Each rotor comprises longitudinally extendingblades 33 and rotates in the direction of the arrow 34.

A pair of similar guide members 35 and 36 extend the length of therotors 3t) and 31 with constant cross-section with one member above eachrotor. Both members are each pivoted about the axes of the rotors onplates 39b and 31b secured to the ends of the members and extending atright angles to those axes. The lower surface 35a of the upper guidemember 35 and the upper surface 36a of the lower guide member 36 providein the full-line positions of those members, guide walls to guide airtwice through the path of the rotating blades of the upper rotor 30.Similar guide walls for the lower rotor 31 are provided by the lowersurface 36b of the guide member 35 in its full-line position and theupper surface 37 of a fixed lower member of the frame 32. The lowerguide walls of the rotors 30 and 31 include portions 36c and 37a on theexit side of the rotor which converge therewith in the direction ofrotation. In operation of the fan unit, the interaction of the rotorsand their respective guide Walls sets up a Rankine vortex in each rotorhaving a core V penetrating the blade envelopes of the rotor, and flowtakes place in the general manner indicated by the flow lines F. Airflow in each rotor will be seen to be generally similar to that of thefan unit of FIGS. 1 and 2, the description of which should be referredto in this connection.

With the guide members 35 and 36 in the full-line positions shown, theirupper surfaces 35b and 36a extend downwardly and well outward of theexterior surface 38 of the frame 32. Rain falling on these surfaces willbe deflected well clear of the rotors 30 and 31. The guide members 35and 36 can be pivoted to the dotted positions shown, in which case theyclose the aperture through the frame 32 against draughts and theweather. Some regulation of the fan unit can be achieved by slightangular movement of the guide members 35 and 36 from the fulllinepositions. It should be noted that in a fan unit as shown in FIG. 3designed on the principles above referred to, power consumptiondecreases as the throughput decreases. Thus regulation of the throughputcan be effected economically without need to regulate the driving motor.

The guide members 35 and 36 can be designed to pivot from closed tooperative position under pressure produced by rotation of the rotors andagainst the bias of their own weight which, when the rotors are stopped,returns the members 35 and 36 to closed position.

FIG. 4 shows an electric motor designed for continuous running andspecifically adapted to drive a pair of coaxial rotor sections 40 and 41extending to either side of the motor. A stator unit designatedgenerally 42 is supported by a pillar 43 and comprises laminations 44aand 4412 with a common winding 45 thereon. Axially extending flanges 46and 47 project from end discs 48 and 49. The discs mount the rotorsections 40 and 41 and substantially close their adjacent ends. Theflanges 46 and 47 surround the stator laminations 44 and carrylaminations 5t) and 51 cooperating therewith. A tubular spindle 52interconnects the end discs 48 and 49 and runs in bearings 53 mountedwithin a tube 54 rigid with the stator unit 42. A support 55 terminatingin a rubber ball is adapted to rest against some adjacent part to giveadditional support to the motor.

It is not essential in a flow machine according to the invention for theguide means for each rotor to be such as to set up a Rankine vortextherein nor for the interior of each rotor to be clear of stationaryobstructions, though these features have been common to the embodimentsdescribed with reference to the drawings. It is possible to provideguide bodies within the rotors to guide the flow through the rotor andthrough the path of the rotating blades. Various arrangements of suchguide bodies are disclosed in application Serial No. 671,114. The motorof FIG. 4 provides a convenient way of supporting such guide bodies.Thus, guide bodies in the two rotor sections may be connected by a shaftextending through the hollow spindle 52.

I claim:

1. A fan unit comprising a shallow open vertical frame, at least twosimilar hollow horizontally extending cylindrical bladed rotorsvertically aligned within said frame and extending over a majorcross-sectional area of said frame, means to rotate said rotors, a firstand a second guide wall extending the length of said rotors positionedadjacent each said rotor and on opposite sides thereof with said firstwall having a first guide surface extending in one direction from oneside of said frame substantially toward a rotor and a second surfaceextending substantially away from the rotor to the opposite side of saidframe and with at least one first guide wall adjacent one rotor joiningat both sides'of said frame with a second guide wall of an adjacentrotor; said first guide wall forming with its adjacent rotor whenrotated a fluid vortex having a core eccentric of the rotor axis andinterpenetrating the rotor blades adjacent said first guide wall toguide air along said first and second surfaces from one side of theframe through the path of the rotating blades into the interior of therotor and thence out through the path of the rotating blades to theother side of the frame whereby air is caused to flow through a majorpart of said frame. 7

2. A unit according to claim 1 wherein some of said guide walls includerotatable guide members extending in an open position beyond said unit;said members when rotated to a closed position covering a side of saidunit.

3. A unit according to claim 2 wherein said guide members are pivotallymounted whereby the weight of the member urges said member to a closedposition when said unit is not operating and air pressure acts on said3,1 5 member to urge it to an open position when said machine isoperating.

4. A fan unit according to claim 1 wherein each said rotor is dividedalong its length into a pair of sections, and having in addition avertical member extending intermediate of said sections from the top ofsaid frame to the bottom thereof supporting said sections and whereinsaid means to rotate said rotors comprises a motor carried by saidvertical member for driving said sections.

5. A unit according to claim 4 wherein said motor has a single internalstator and rotor means surrounding said stator mounted on each saidsection.

References Cited in the file of this patent UNITED STATES PATENTSFOREIGN PATENTS France Aug. 6, 1910

1. A FAN UNIT COMPRISING A SHALLOW OPEN VERTICAL FRAME, AT LEAST TWOSIMILAR HOLLOW HORIZONTALLY EXTENDING CYLINDRICAL BLADED ROTORSVERTICALLY ALIGNED WITHIN SAID FRAME AND EXTENDING OVER A MAJORCROSS-SECTIONAL AREA OF SAID FRAME, MEANS TO ROTATE SAID ROTORS, A FIRSTAND A SECOND GUIDE WALL EXTENDING THE LENGTH OF SAID ROTORS POSITIONEDADJACENT EACH SAID ROTOR AND ON OPPOSITE SIDES THEREOF WITH SAID FIRSTWALL HAVING A FIRST GUIDE SURFACE EXTENDING IN ONE DIRECTION FROM ONESIDE OF SAID FRAME SUBSTANTIALLY TOWARD A ROTOR AND A SECOND SURFACEEXTENDING SUBSTANTIALLY AWAY FROM THE ROTOR TO THE OPPOSITE SIDE OF SAIDFRAME AND WITH AT LEAST ONE FIRST GUIDE WALL ADJACENT ONE ROTOR JOININGAT BOTH SIDES OF SAID FRAME WITH A SECOND GUIDE WALL OF AN ADJACENTROTOR; SAID FIRST GUIDE WALL FORMING WITH ITS ADJACENT ROTOR WHENROTATED A FLUID VORTEX HAVING A CORE ECCENTRIC OF THE ROTOR AXIS ANDINTERPENETRATING THE ROTOR BLADES ADJACENT SAID FIRST GUIDE WALL TOGUIDE AIR ALONG SAID FIRST AND SECOND SURFACES FROM ONE SIDE OF THEFRAME THROUGH THE PATH OF THE ROTATING BLADES INTO THE INTERIOR OF THEROTOR AND THENCE OUT THROUGH THE PATH OF THE ROTATING BLADES TO THEOTHER SIDE OF THE FRAME WHEREBY AIR IS CAUSED TO FLOW THROUGH A MAJORPART OF SAID FRAME.